The current prior art shall be explained below by an example in conjunction with FIGS. 1, 2a and 2b: 
FIG. 1 shows a fifth wheel coupling 101 in perspective view. The fifth wheel coupling has a fifth wheel coupling plate 102 with an entry opening 103, into which a kingpin (not shown) of a trailer is introduced and can be locked there. For this, underneath the fifth wheel coupling plate 102 is arranged, say, a lock bar 120, which after the kingpin is inserted brings about a locking of the kingpin together with a closure hook (not shown).
To activate the lock bar 120, it is known from the prior art to provide an activating device 130, which has a two-part pull handle 132, which essentially consists of a pull lever 140 and a safety lever 150. On the safety lever 150 is arranged a handle 156. The pull handle 132 extends through an opening 110 in a side wall 104 of the fifth wheel coupling plate 102. Inside this opening 110, the pull handle 132 can be both shoved in the lengthwise direction of the pull handle 132 (arrow P1) and swiveled in the horizontal direction (arrow P2).
FIGS. 2a and 2b are simplified partial views of the fifth wheel coupling 101 shown in FIG. 1 with an activating mechanism 130 according to the prior art, as is described for example in DE 10 2008 000 799 A1.
The pull lever 140 and safety lever 150 can be moved relative to each other in the longitudinal direction, and the pull lever 140 and the safety lever 150 are joined to each other by a tension spring 159. By another tension spring 149, the pull lever 140 is fastened to a component (not shown) of the fifth wheel coupling plate 102. The force of this tension spring 149 is greater than the force of the tension spring 159.
The pull lever 140 has a holding means 142 in the form of a retaining lug, by which the pull lever 140 can bear against the inner surface 106 of the side wall 104 of the fifth wheel coupling plate 102 when the lock bar 120 is in the locking position as shown in FIG. 2a. The pull handle 132 is in its locked position.
The pull lever 140 is hinged by two connection levers 134a, 134b to the lock bar 120. In the locked position of the pull handle 132, the swiveling ability of the pull handle 132 in the opening 110 is blocked by the safety lever 150, which projects to the side relative to the pull lever 140, so that an unintentional loosening of the fixation of the pull handle 132 and thus a loosening from the locked position is prevented. The dimensions of pull handle 132 and opening 110 in the locked position of the pull handle 132 are adapted to each other such that no swiveling of the pull handle 132 is possible.
In order to move the lock bar 120 from its locking position, the pull handle 132 must be pulled out from its locked position into a release position. For this, it is necessary for the pull lever 140 to swivel about the pivot point 138 in the arrow direction P3 in order to loosen its fixation within the opening 110, so that the retaining lug 142 is detached from the inner surface 106 of the side wall 104 and the pull handle 132 as a whole can be pulled outward. It is therefore necessary to pull out the safety lever 150 by means of the handle 156 so far relative to the pull lever 140 that the safety lever clears the opening 110 and the pull lever 140 can swivel in the region of the opening 110 (arrow P3). Only in this pull-out position of the safety lever is it possible to swivel the pull handle 132 freely.
After pulling out the pull handle 132, which brings the lock bar 120 to its open position, the pull handle 132 can be fixed in its release position by means of a retaining lug 144. After letting go of the handle 156, the safety lever 150 is pulled back by the tension spring 159 into its position of rest.
When the kingpin is introduced, the retaining lug 144 of the pull handle 132 is disengaged and the pull lever 140 is pulled back by the tension spring 149. If order for the pull handle 132 and thus the pull lever 140 with its retaining lug 142 to move through the opening 110 into the fifth wheel coupling 101, the pull handle 132 must be elongated, i.e., the safety lever must be placed in its pull-out position. In this pull-out position, the pull handle 132 must be pushed back through the opening 110, which leads to the problem that large frictional forces must be overcome and the pull handle 132 can become skewed and get jammed in the opening 110. Furthermore, it is necessary to overcome the spring force of the tension spring 159.